KISS1 and endometriosis: A lack of KISS1 and KISS1R in the endometrium can cause abnormal expression of matrix metalloproteinases (MMPs), vascular endothelial growth factor (VEGF), and other molecules, leading to disturbed invasion, migration, and angiogenesis of the endometrium; furthermore, abnormal endometrial hyperplasia, endometriosis, and uterine endometrial carcinoma were related to this abnormality.